Non-receptor tyrosine kinases (NRTKs) function as tightly regulated, integrating switches in cellular signal transduction. Here we focus on representatives of three NRTK families, which have distinct multi-domain architectures: Jak-family kinases, Focal Adhesion Kinase (FAK), and the Tec-family member ITK (Il-2 inducible tyrosine kinase). Our longterm goals are to elucidate autoregulatory mechanisms of NRTKs at a structural level, to understand how these regulatory mechanisms are disrupted in cancer, and to use structural insights to facilitate discovery of novel inhibitors. With our collaborators, we are combining the tools of structural biology, biochemistry, cell biology, and chemistry in a unified way to advance these goals. We propose three Specific Aims. First, we will discover how Jak kinases recognize their cognate cytokine receptors and how they are regulated by interactions among their constituent domains. We have crystallized an Nterminal fragment of Jak2, and have also prepared a complex of this portion of Jak2 with the cytoplasmic tail of the erythropoietin receptor for structural analysis. Our studies of Jak regulation build on our recently determined structure of a linker/pseudokinase regulatory module, and through elucidation of the structure of essentially full-length Jak2, we will explain how the this module controls the activity of the adjacent kinase domain, and how this control is disrupted by the V617F mutation in myeloproliferative neoplasms. Second, we will determine structurally how focal adhesion kinase (FAK) is activated by PI(4,5)P2.
This aim builds on our determination of the structure of FAK in its autoinhibited state, and our discovery that it binds and is activated by the PI(4,5)P2. Third, we will elucidate the structure an SH3-SH2-kinase fragment of Itk in order to understand its regulation and to facilitate inhibitor discovery. Based on our structural insights, we are developing irreversible inhibitors specific for Jak3 that may be useful in treatment of autoimmune and inflammatory disorders.

Public Health Relevance

We are studying three non-receptor tyrosine kinase families, proteins that control cell proliferation, differentiation and migration. Understanding how these proteins work, and how they are altered by mutations in cancer and other diseases will improve human health, in the long term, by aiding development of drugs to modulate their activity. Jak kinases are key for production of both red blood cells and white blood cells, and mutations in Jak2 cause blood cancers. We are studying how one of these mutations V617F, alters Jak2. Focal adhesion kinase is overproduced in many cancers, and is important for their ability to invade normal tissues and to metastasize. We are working to understand how it is normally activated, in order to better understand how it can be de-activated in cancer. We are working to develop novel drugs that specifically target Jak3, an important target for drugs in autoimmune and inflammatory diseases such as asthma and rheumatoid arthritis.